BeanListHandler#handle(ResultSet) is not optimal

• Key: DBUTILS-37
• Type: Improvement
• Status: Closed
• Resolution: Fixed
• Priority: Minor
• Assignee: Dan Fabulich
• Reporter: Julien Aymé
• Fix Version/s: 1.2

Description

I use the BeanListHandler for huge ResultSets (about 1000000 rows), and I searched through the code to see if I could gain little time.

It appeared to me that the following code - in BeanProcessor.class - was executed too many times:

PropertyDescriptor[] props = this.propertyDescriptors(type);
        ResultSetMetaData rsmd = rs.getMetaData();
        int[] columnToProperty = this.mapColumnsToProperties(rsmd, props);

for the following reason.
Since BeanListHandler extends GenericListHandler, the method #handle(ResultSet) calls #handleRow(ResultSet) for each row in the ResultSet,
which in the case of a BeanListHandler, calls RowProcessor#toBean(ResultSet, Class),
which itself calls BeanProcessor#toBean(ResultSet, Class).

A very simple way to make the BeanListHandler#handle(ResultSet) method faster is to override the GenericListHandler#handle(ResultSet) method by this code:

public Object handle(ResultSet rs) throws SQLException {
        return this.convert.toBeanList(rs, type);
    }

This way, the code I showed would be called only once, as it would not call BeanProcessor#toBean(ResultSet, Class) for each row but BeanProcessor#toBeanList(ResultSet, Class).